_______________Detailed Description

The MAX836/MAX837 micropower voltage monitors

contain a 1.204V precision bandgap reference and a

comparator (see the

Typical Operating Circuit). The

only difference between the two parts is the structure of

the comparator output driver. The MAX836 has an

open-drain N-channel output driver that can be pulled

MAX837’s output is push-pull, and can both source

and sink current.

Programming the Trip Voltage

impedance allows large-value resistors without compro-

mising trip-voltage accuracy. To minimize current con-

sumption, select a value for R2 between 500k

Ω and

1M

Ω, then calculate R1 as follows:

threshold trip voltage (1.204V).

__________Applications Information

Adding Hysteresis

Hysteresis adds noise immunity to the MAX836/MAX837

threshold trip voltage. Figure 2 shows how to add hys-

teresis to the comparator. The technique is similar for

R1 = R2

V

V

-1

TRIP

TH









4-Pin Micropower Voltage Monitors

4

_______________________________________________________________________________________

____________________________Typical Operating Characteristics (continued)

_____________________Pin Description

NAME

FUNCTION

1

GND

System Ground

2

System Supply Input

PIN

3

IN

Noninverting Input to the Comparator.

The inverting input connects to the

internal 1.204V bandgap reference.

4

OUT

Open-Drain (MAX836) or

Push-Pull (MAX837) Output

GND

OUT

IN

MAX836

R2

R1

R1 + R2

R2

NOTE: UNITS ARE OHMS AND VOLTS

0.1

µF

0

200

400

600

800

1000

1200

1400

1600

1800

24

8

OUT RISE/FALL TIME vs.

SUPPLY VOLTAGE

610

35

9

711 12

FALL TIME

RISE TIME

MAX837 ONLY

40

160

140

120

100

80

60

-60

-20

60

vs. TEMPERATURE

TEMPERATURE (°C)

20

-40

0

80

40

100

1mV/

µs

10mV/

µs